Telephone system



Aug. 1, 1933.- J MCKS ET A; 1,920,226

TELEPHONE SYSTEM I Filed Dec. 11, 1931 4 Sheets-Sheet l OTC Harri G. 5%

1933- J. WICKS ET AL 1,920,226

TELEEHONE SYSTEM Filed Dec. ll, 1931 4 Sheets-Sheet 2 InuEnZur-s John Wicks ii-J Aug. 1, 1933. J. WICKS ET AL TELEPHONE SYSTEM Filed Dec. 11, 1951 4 Sheets-Sheet 3 Aug. 1, 1933. J. WICKS ET AL TELEPHONE SYSTEM Filed Dec. 11, 1931 4 Sheets-Sheet 4 ENE h I Inuen urs- John Wicks E3113 (3. Euers Patented Aug. 1, 1933 PATENT OFFICE TELEPHONE SYSTEM John Wicks, Oak Park, and Harry G. Evers, Chicago, IlL, assignors, by mcsne assignments,

Associated Electric Laboratories, Ina,

Chicago; 111., a Corporation of Delaware Application December 11, 1931. Serial No;

.21 Claims. (01. 179-27.)

This invention relates to telephone systems'in general, butis concerned particularly with multioiiice telephone systems which include suboffices and in which certain classes of connections are established over a train of automatic switches and through one or more tandem oiiices.

The object of the invention is to provide greater flexibility and additional service-features for systems of the above type, by means of new and improved circuits and apparatus. This includes the provision of a novel connector repeater andiimproved trunking and switching apparatus for sub-oifices of the single-trunk and single-switch type. i

General description Among the features of the connector are the arrangement for repeating impulses over one talking wiper and an auxiliary wiper, and for controlling the dialling and ringing operations of the succeedingapparatus over the other talking wiper. This arrangement permits the switch to extend connections over combined automatic and toll-trunking systems in which the manual cord circuits are arranged for tip-and-sleevedialling and dialling and ringing control over the ring contacts of the plugs. The connector is also provided with a novel auxiliary impulsing arrangement which serves both to correct for any irregularity in the received impulse and to delay the repeated impulses long enough to permit the switch ahead to get into condition to receive the impulses. V e V The features of the sub-office apparatus include the arrangement for revertive calling, the provision of secret service on. all except revertive calls, the provision of a visual to indicate dialling condition in revertive calls, and the assooffice trunk to make this equipment available for both incoming and revertive calls.

The foregoing features and others not specifically mentioned will be described in more detail hereinafter.

Description of drawings The invention is illustratedin the accompanying drawings by a multi-office telephone system in which a tandem office also serves as a switch ing center for a number of single-trunk semiautomatic sub-oflices. The sub-ofiices are of the same general type as that shown in Patent No. 1,787,430, granted January 6, 1931, to FAppelius. using mechanical switcheahowever, instead of manual trunks; such as are commonly used in' elation of the ringing equipment with the sub-.

the relay-type switch shown in the patent, and. with further modifications to incorporate the various new features above referred to. The trunking system is generally similar to and is' designed to operate in conjunction with the system 0 of the type disclosed in the co-pending application of J. Wicks, Serial No. 540,992, filed May 29,

Referring now to the drawings, Figs. 1, 3, and 4 show equipment located at the tandem ofiice, 5 and Fig. 2 shows equipment locatedat a suboffice. Fig. 5 is a layout diagram showing the manner in which the various sheets of drawings should be assembled to show the cooperation between the different circuits.

In Fig. 1 is shown a relay group RG associated with a trunk line extending from the tandem office to the sub-office shown in Fig. 2. One

branch of the trunk extends to jack J at the manual switchboard, and a second branch extends to the banks of the connector repeater shown in Fig. 3. Supervisory lamps L and L1 are associated with the jack J at the inanual switchboard. The cord circuit CC, position equipment PC, and operators telephone circuit OTC, which are shown inskeleton formgmaybe exactly the same as the correspondingly designated apparatus shown, in Fig.2 of the Wicks application previously mentioned. Thecord circult is adapted for answering and extending calls over trunk lines such as the ones shown in Fig. l and Fig. 4; 7 e

Referring now to Fig. 2, there is shown a subofiice selector switch S5 which has access to ten subscribers lines of which only those extending to substations A and B have been shown. The switch is mechanically similar to the well-known type rotary lineswitch with wiper movement in one direction only. The sub-oilice is designed to I operate from a twelve-volt battery whichis connested over the upper trunk conductor to a fortyeight-v0lt battery at the tandem exchange whenever the equipment is idle. This arrangement provides for charging the sub-office storage battery, ancLaccordingly, eliminates all charging equipment at the sub-ofiice.

Connector repeater, CR, shown in Fig. 3, is mechanically similar to the usual Strowger ver tical-and-rotary type connector. This switch is adapted to operate in a system in which impulses 105 are transmittedover a loop,'and in which the various auxiliary operations are centrolled by thereto may be extended by way of a repeater R1 and selector ISl, shown in Figs. l and 5, respectively, of the said Wicks application. The connector repeater has access to the sub-office trunks, such as that shown in Fig. 1, and to trunks extending toother oflices of which one is shown in Fig. 4.

In Fig. 1 is shown a relay group RGL, associated with a trunk connecting the tandem office with another automatic ofice. One branch of the trunk terminates in jack J1 at the manual switchboard and is connected with bya cord circuit, such as cord CC. A second branch of the trunk extends to the banks of the connector repeaters,Fig. 3, over which calls. from other oilices are extended. The trunk terminates in the distant ofiice in a switch CR1, which may be a connector similar to connector CR or any other suitable switch. The distant end of the trunk is accessible in the banks of connector switches of the usual type. r v

' Detailed description Having briefly described the invention, the operations involved in establishing various types of connections in a system embodying the same will now be described in detail. Consideration will first be given to a call originating at the station of a suboffice subscriber-for example, at sta tion A.

Call originating at the sub-ofi'icc .Upon the initiation of a call at substation A, a circuit is completed from battery, resistance 214, contacts 242, contacts 259, conductor 270, through the telephone instrument at substation A, conductor 271, contacts 249 and 232, relay 209, wiper 219 in normal position, to ground. It may be noted at this time that when any sub-exchange subscriber initiates a call a similar circuit is com-- pleted for relay 209 since the respective conductors of the various lines are connected in parallel by way of contacts 246 to 265, inclusive, of relays-210 and 211. Upon the completion of the circuit above-traced, relay 209 operates, shortcircuits contacts 242 by closing contacts 243 to prevent a premature interruption of its own circuit, applies ground to holding conductor 274 at contacts 2&4, and at contacts 245 completes a circuit which may be traced from ground. contacts 222, 225, 235, 238, 245, and 239 to relay 207 and battery. Relay 207 operates and at contacts 240 connects stepping magnet 212 in parallel with'itself. The stepping magnet operates, advances the switch wipers ahead one step, and

interrupts the circuit of relay 207and contacts 239. Upon the first step of the wipers, off-normal contacts 217 close so that a circuit is completed for relay 207 independent of contacts 245 of relay 209. The connection of ground to conductor 274 energizes relays 208, 210, and 211. The latter two relays open points in the circuit of relay 209, which accordingly restores. Before the restoration of relay 209, however, the wipers of the switch are advanced as above described, and a new circuit is completed for relay 207. Relay 207 and magnet 212 inter-act, as

- above described, and advance the wipers of the switch step by step until the calling line is found.

Upon wipers 218 and 220 engaging the contacts of the calling line, a circuit is completed from battery at the main exchange, winding of relay 111, contacts 147 and 136, trunk conductor 158, winding of relay 201, wiper218, contact 266, con-- ductor 270, through the loop at the calling station, conductor 271, contact 268, wiper 220, to ground at contacts 228. exchange may release momentarily when relay '208 disconnects the sub-ofiice battery from the upper trunk'conductor, and, if so, this relay will r'eoperate in'ser'ies with relay 201 of the suboifice over the above-traced circuit. Relays 201 opens the stepping circuit at contacts 222 to prevent any further movement of the switch wipers, and at contacts 221 completes a circuit for relay 202. Relay 202, among other things, connects wiper 220 through to trunk conductor 159, thereby replacing the ground at contacts 228 by ground through relay 106 which is connected to the trunk conductor byway of con tacts 153, 119, and 123. Relay 106 operates, completes a circuit for busy lamp L at contacts 128,

prepares a circuit for relay 107 at contacts 130,

connects guarding ground to test conductor 161 at contacts 132 to mark the trunk busy in the banks of the connector repeaters, and completes a circuitfor line lamp L1 at contacts 133. The two lamps glow to indicate the call on the trunk.

The operator will answer the call by inserting the answering plug of a cord circuit, such as CC, into jack J. An operating circuit is completed for relay 105 byway of contacts 116 and battery on the sleeve of the cord. When the plug is fully inserted in the jack, contacts 113 close and ground is, applied by way of contacts 130 to relay 107. This relay operates, completes a holding circuit for itself at contacts 138, disconnects trunk conductcr l58from relay 111 and connects it to battery through impedance 112, prepares the supervisory circuit byclosing contacts 141, and opens the circuit for lamp L1 at contacts 138. The lamp .two talking condensers.

Relay 111 at the main 7 Further operations will now depend upon,

. whether the call is for a subscriber in the subofiice or for a subscriber in one of the other ofiices. In the latter case, the operator will complete the call either by inserting the call ing plug of the cord circuit into'the jack of the calledline or inserting "the plug .into the jack of an idle trunk extending to the office in which the called subscriber is located. In either case, the connection will be completed by the opera tor in known manner and the subscribers may talk over the circuit. previously described.

When the calling subscriber hangs up, the loop circuit of the calling station will be opened, and, accordingly, relay 106 willrcstore. Relay 106 opens the circuit of relay 107 and the latter relay restores and reconnects relay 111 to conductor 158. In the sub-oihce relay 201 releases upon the opening of the calling subscribers loop and in turn opens the circuit of relay .202. Relay .202 completesthe circuit for relay 207 as pre viously traced, and the latter relay again closes the circuit for stepping magnet 212. Magnet 212 and relay 207 cooperate to advance the wipers step by step until the home bank contact is reached, whereuponwiper 219 is stepped off of the last of the multiply connected contacts to open the. circuits of relays 208, 210, and 211. When the wipers reach normal position, the circuit of relay 211 is opened at off-normal contacts 217 and no further wiper movement takes place. Relay 111 at the tandem oflice now operates in series with the battery at the sub-office and at those described in previous connections.

position and that dialling may take place. operator will then actuate her ringing key, which. "incord circuits of the type referred to ,results in without efiect.

contacts 157-completes acircuit for relay 110 to ground at contacts 113 of the jack Relay 110 operates, completes a holding circuit for itself at contacts 150, disconnects relay 111 from conductor 158 at contacts 147, and completesthe supervisory circuit at contacts135; The supervisory lamp in the operatorscord circuit is now lighted-due to the application of ground by way of contacts 140, 135, and 127 and the lower low resistance winding of relay. 105 to the sleeve of the cord Theupper high resistance winding of. the sleeve relay is shunted by this. ground and the supervisory lamp of the cord c' "cuit is oper ated in a well-known manner. It may be noted that upon the release of relay 111, ringing current is supplied to the uppertrunk conductor by way of the upper. winding of relay 109, contacts 142, 154, 148, and 136. This is without effect, however, as'the sub-office battery is connected to this trunk conductor, and, further, wiper 2 18'is standing on its home contact, and is, therefore, not in engagement with any of the line contacts. On. noting the lighted condition of the supervisory lamp the operator will withdraw the plug of the cord fromv the jack, thereby opening contacts 113 and permitting re lay 110 to restore. Relay 105 alsorestores and thetrunk apparatus is in condition to receive the next call. 7

In the case of acall between subscribers in the sub-office, the operations taking place upon the initiation of the call are exactly the same as After answering the call, however, the operator, instead of further extending it"by means of the cord circuit, will merely request the calling subscriber to hang up his receiver for a moment.

Upon complying with this request and restoring his receiver, the sub-ofiice selector will restore as before described, and upon this switch reaching normal position the supervisory lamp of the cord circuit will be operated to indicate that the said office switch has reached normal The the opening of the sleeve circuit and the application of battery through a lowresistance to the ring-side of the line. Relay 105 restores and connects relays 101 and 102 to the ring side of the line, and both these relays operate. 101 hasno function in operating at this time,

but relay 102 connects generator GEN to-trunk contacts 236 and prepares the stepping circuit at contacts 237. Relay 203, on operating, opens the circuit of relay 210 at contacts 230, and at contacts 229 opens one'point in the circuit of relay 111. The operator then restores her ringing key to normal, whereupon relays 101 and 102 release and-relay 105 reoperates.

Relay 205 of the sub-office selector is now maintained operated over a circuit which extends to battery by way of conductor 159, contacts 123, 119, 152, and 146. As in the previous case, ringing current is applied to trunk conductor 158, but is Relay The operator now actuates the dialling key of the cord circuit, which opens the sleeve circuit and applies battery through a'high resistance to the ring conductor of the trunk. Re-

lay 105 releases and connects relays 101 and 102 to the ring conductor, and relay 101 operates.

Relay 102, which is marginally adjusted, does not operate due to the resistance in the sleeve circuit. Relay 101 completes a circuit at contacts 114'101' relay .104, connects battery through a resistance to the sleeve conductor at contacts opens the ringing circuit at contacts 117, and connects the tip of the jack through to trunk conductor 159 at contacts 118. It will be recalled that when the called subscriber hung up his as above described shifts the circuit of relay205 i so that it extends through impulse contacts of the operators dial. Relay 104 also operates upon the closure of its circuit by relay 101 and a circuit is closed at contacts 125 for relays 103 and 104 in series. Relay 103 does not operate as it is short-circuited by the ground at contacts 114.

The operator dials the digit assigned to station B, and thecircuit previously traced for relay 205 is interrupted accordingly at the impulse contacts of the operators dial. Relay 205 responds, and, each time it releases, a circuit is completed by way of ground, contacts 222 225, 235 and 237jwinding of stepping magnet 212, to battery. Stepping magnet 212 responds to these impulses and advances the wipers step by step to the set of contacts in which the called line terminates.

fter dialling the number of the wanted subscriber the operator will restore her dialing key, thereby reapplying battery to the sleeve and removing the battery from the ring conductor. Re-

accordingly operates and disconnects relays 101 and 102 from the trunk. Relay 101, on restoring, reestablishes the holding circuit for relay 205 of the sub oiiice selector by closing contacts 119, closes the ringing circuit at contacts 117, and removes the short circuit from around relay 103 at contacts 114. Relay 103 operates and at contacts 124 opens the circuit for relays 101 and 102 so that these relays will not reoperate in case the operator inadvertently actuates her ringcontacts 142, 154, 148, and 136, conductor 158,

wiper 218 of the sub-ofiice selector, contact 267,

conductor 272, through the bell and condenser at the called substation B, conductor 27330011- since relay 211 is operated and the calling and lines are connected through two small The condensers, however,

the called condensers in series.

permit the calling man to hear the ringing current and thus be advised that the called subscriber is being signalled.

When the called subscriber answers, a direct current path is closed at the called substation and relay 109 operates. The ringing circuit is opened a contacts 142. the upper trunk conducto: is extended to the talking condenser and battery impedance 112 at contacts 143, a locking "selector release.

relay 109 at contacts .144, and'the lower trunk conductor is connected to ground through relay 108 uponthe closure of contacts 145. At the suboflice, relay 201 operates and completes a circuit for relay 202. Relay 202 opens the circuit of relay 211 at contacts 223 and, that relay accordingly. restores. Relay 211 on restoring sl1ort-circuits the various condensers through which the sub-office lines were connected during the ringing by closing contacts 256 to 265, inclusive. Relay 202 in addition to opening the circuit of relay 211 also disconnects trunk conductor 153 from impulse relay 205 and connects it instead to wiper 220 of the sub-office selector. Relay 10 8 of the trunk relaygroup now operates over the called subscribers loop andopens the supervisory circuit at contacts 140. The subscribers maynow talk as their respective lines are directly connected over contacts relays 210 and 211. Talking currentfor both'subscribers fed through the impedance and relay at the tandem ofice over the circuit previously described. When desired, the operator may tall: to the subscribers, the circuit in this case being the same as that over which the operator talked to the calling subscriber. 7

At the termination of the call, both subscribers hang up their receivers and relay 108 of the trunkrelay group and relay 201 of the sub-office Relay 108 completes a circuit for shunting the upper high resistance winding of relay 105 by closing contacts 140 and the supervisory lamp of the cord circuit is lighted in the usual way. The release of relay 201 permits relay 202 to restore, and, since offnormal contacts 217 are closed with the switch out of home position, relay 207 Will operate and complete a circuit for stepping magnet 212. The magnet and relay will inter-act until the switch wipers are stepped to normal position in the manner previously described, whereupon the stepping of wiper 219 from the multipled contacts of its banks will remove ground from holding conductor274 and permit the various relays of the sub-. office selector to restore. The operator may then withdraw the plug of the cord circuit from the jack, whereupon the operated relays of the trunk relay group will restore and place the trunk in condition toreceive the next call.

Calls to sub-oflicc subscribers The operator at the tandem ol'lice may extend calls to sub-ofiice subscribers lines in exactly the same manner as the previously described revertiye' call. It will be recalled that in the preceding connection the calling subscriber first hung up and placed the equipment in normal condition, whichis the condition which prevails when the operator is extending an incoming call to a line.

In connections of this kind, however, the operator does not ring prior to dialling, and consequently relays 204 and 203 of the sub-oilice selector are not operated. Since relay 203 is normal, relays 210 and 211 will remain operated throughout a connection and the various subment provides for secret service in connections ofiice lines will be separated due to the opening of-contacts 246 to 265, inclusive. This arrangeof this kind as the condensers through which the upper line conductors are connected are too small to permit the transmission of enough current to connection spondsto the impulses and raises the switch .302 through to rotary magnet 317 by way of concircuit is completed for the lowerwinding of changes, however, will be completed automatically by operators in the distant office. In this case a connection will be extended over one of the inter-office trunk, lines to the connectorrepeater CR, Fig. 3. A control loop for operating relay'302 will be completed at the repeater terminating the incoming trunk by way of condoctors 385 and 387 andcontacts 328 and 330 of relay 301. Relay 303, which has its two windings connected in series with the two windings of relay 302, does not operate at this time as it is differentially wound. Relay 302 operates and completes a circuit for relay 305 at contacts 334. The closure of contacts 333 is without eiTect at this time since relay 310 isnot operated and conthe impulsing circuit at contacts 342, and applies ground to release trunk conductor 386 at contacts 343. Battery through resistance 320 is connected to relay 301 at contacts 340, but this is inefiective tooperate the relay at this time due to the shunt by way of contacts 353, 336, and 375, to ground. Ground is applied. to local holding conductors 392, atcontacts 341, and by way of contacts 348 operates relay'306. Relay 306 looks to the conductor 392 by way of contacts 346 and 395 and at contacts 347 completes a circuit for relay 307. The operation of relays 306 and 307 at this time is without effect.

The calling operator now dials the first digit of the number designating the wanted sub-oilices and the circuit of relay 302 is interrupted intermittently in accordance with the value of the digit. Relay 302 responds and transmits the first, impulse of the series by way of contacts 335, 342, 382, 324, winding of relay 308, vertical magnet 316, tobattery. Relay 308 is slow releasing and operates in response to the first impulse, and remains operated throughout the series of impulses. A circuit is completed at contact 349 over which the second and succeeding impulses of the series are transmitted when off-normal contacts324 open and contacts 325 close on the first vertical step of the wipers. Magnet 316 rewipers step by'step to the called level. Shortly after the last impulse of the series, relay 308 restores and connects the impulse contacts of relay tacts 350 and 365, windingof relay 313, and contacts 380. V

The operator now dials the second digit designating the wanted sub-ofiice and relay 302 rethroughout the series. Relay 313 closes a circuit at contacts 368 for slow-releasing relay 314, and

the latter relay also operates. Magnet 317 steps the wipers around to the contacts of the called trunk, which in the present instance are assumed to be the contacts in which conductors 160-163 terminate. The operations beyond this point will depend upon whether the trunk to the sub-office is busy or idle at this time.

Assuming first that the called trunk is busy,

therewill be ground on the contact engaged by Wiper 390 dueto the operated condition of relay 106 of the trunk relay group or to the closure of contacts 113 of the jack springs. Relay 313 01' the connector-repeater will restore shortly after the last impulse of the series, and open the circuit of relay 314. After relay 313 releases, and before 'tacts35'7 are open. Relay 305 operates, prepares relay 314 restores, a circuit is completed from ground on the test contact, wiper 390, contacts 373,363, 368, and 377, winding of busy relay. 312,. to battery. Relay 312 operatesv and completes a, holding circuit foritselii by way of contacts 362' and 370. Relay 312 also. connects the test wiper a circuit for rotary magnet 317. The rotary magn t operates and advances wipers of the switch. one step, att'he same opening the circuit of relay 01:. at contacts The impulse transmitted to the rotary magnet serves to energize relay 31 1 which is connected in parallel with theinagnet so that this relay remains operate In the present instance, since only. one trunk is involved, thetestcontact of the group succeeding the one in which the trunk terminates is connected to ground through a r'=--,

sistance. Relay 312 remains operatecl'overthe previously-traced heldingcircuit whi h includes contacts 377, 366, 362, and 370, wiper 390, test contacuto ground through resistance 300. The circuit for relay 311 is again completed, but due 'to its marginal adjustment, relay 311 does not operate in serie, with r istance 300. The wipers of the switch are acooi igly'brought to rest on this idle set of contacts, and relay 31d restores after a short interval and transfers the holding circuit of relay 312 tcjgrounded holding conductor 3 Relay 312 applies busy tone to the lower talking conductor the switch by closing contacts 393. This informs the calling operator that the called ti ii: is not available and she is expected to release the connection, will be. explained sub. .equently. T

In case the trunkto the, sub-officeis not busy when the con ection above described is completed, there our i on thetest contact, and consequently r 3312 or the connectorrepeater does not operate. When relay 314.1'estores, switching relay of the c .ector repeater and relay of trunk. it y group will operate in. series over a circuit y traced from battery. relay 110, contacts and ,131, conductor wiper 330, contacts s 3, 315, and contacts T to grou 392. Relay 315 connects up ers 333, and 391 by closing contacts 374, 37c, and 383,lopens the circuit of busy-testrelay 312 at contacts 3'77, applies ground directly to test wiper 330 at contacts 37 completes a lOClilllgflllCllli; for its lower winding at contacts 379, disconnects the rotary magnet contacts 330; and prepares thecircuit for relay 33.0 at co ts 381. Relay 11'3 discona nects relay 111 1'1 conductor contacts 147, closes .a point in the ringing; circuit at con tacts 148, closes a loc tacts 150 so that the release of relay 111 will not inter 'upt its i rouit, prepares a supervisory circult at contacts prepares a holding circuit for relays and 1.09 atcontacts 151, and at contacts 152 trunk conductor. 159 through, to battery. Sleeve relay 105 of the trunk relay group-operates, over a circuit whic traced from battery, resistance 320, contacts 340, 353, 336, and 376, wiper. 389, conductor 162, contacts 116, upper winding of relay 105, to ground. Relay o3 tin immediately shunts its upper high resistv nce winding by closing contacts 137 which connects ground to the lower .lowre- 157, 129, 01,;test contactand test upper of relay .nection.

i may be 1 ed conductor circuit for itself at con-- 1 maybe sistance winding of the relay. It will be recalled that-relay 301.01" the connector repeater was,pre-.

viouslyprevented from operating by the shunt due to the ground connection at contacts 375.

relay 205 operates'in response to the connection of battery to trunk conductor 159, and this-relay. prepares the switch to respond to impulses as previously described for the manually completed con- The calling operator now dials the number of the wanted sub-ofiice subscriber and rela 302' responds as it did for the preceding digits. At. each interruption oiits circuit, relay 302 restores and completes a circuit from ground, contacts 342, 331, winding of slowerelease relay 310, to battery. Relay 310 operates and remains operated throughout the series of impulses. Relay 310 connects ground to one side of condenser 327 at contacts 357 and completes a circuit for relay 309 at contacts358. Relay 309 operates, prepares the impulsing circuitby closing'contacts 352, com pletes a shunt circuit for relay 301 at contacts 354, applies battery through resistance 323, contacts 355, and wiper 331, conductor 160. The cir' cuitor sleeve relay 105 is opened at contacts 353 and that relay restores and connects up relays l01 and'102 at contacts 126. The battery connected to wiper 391 of the connector repeater now operates relay 101 over conductor 160 and contacts 126, but, due to the value of resistance 323, marginal relay 102 does not operate in this circuit. Relay 10l transfers the operating circuit of-relay 205 of the sub-office selector from the previously described circuit to the impulsing contacts of the selector repeater by way of contacts 118, conductor 163, wiper 388, contacts 374, 352, 345, 336, and 376, wiper 383, conductor 162, contacts 115, and through the resistance, to battery. The fore-' going operations all take place responsive to the relay 302 releasing for the first impulse. When relay 302 reoperates at the end of the impulse, relay a is connected to condenser 327 by way of contacts 33; Relay 30 lis a sensitive relay and the current flowing through the winding of the, relay to charge condenser 27, which, as previously stated, i now connected to ground by way of contacts 357, operatesthe relay, Relay 304 opens the holding circuit of relay 306 at contacts 335. Relay 306 releases, interrupts the previously traced circuit for the impulse relay of the substores after a slight delay due to the parallel circuit including resistance 344, which makes the relay slow ,to release and completes the original energizing circuit of relay 306' at contacts 348.1

Relay 306 reoperates and closes the impulsing circuit at contacts 3 15, thereby terminating the open impulse. In case more than one impulse is to be transmitted, relay 302 releases for the second im: pulse and completes a discharge path for condenser 327, by way of contacts 332 and resistance 321. Relay 304: restores upon the opening of its circuit if it has not previously restored, and relay 305 will again be locked up by way of contacts 345 and 395. Thereoperationof relay 302 at the-termination of the second impulse will resultin the momentary operation of re1ay'304 and release of relay 300, which results in a second impulse being transmitted to the sub-office se- 1 relay 105 at contacts 140.

lector. The remaining impulses will be repeated 'in-the same manner. It will be noted that each repeated impulse is. delayed until the received impulse is completed, andalso that the length of the repeated impulse will depend upon the adjustment of relay 307, which controls the reoperation of relay 306 after each repeated impulse Relay 304 is only required to operate momentarily and. the length of the impulses is independent of the operating characteristics of that relay.

It will also. be noted'that the operation of relays 309 and 310 .during the transmission of impulses is equivalent to the operation of the dialling key of a cord circuit in manually established connections. The impulse relay of the sub-office selector operates in response to the impulses and sets the switch in exactly the same manner as for the previously-described manually-completed connection. Shortly after the last impulse of the series relays 309 and 310 will release. The removal of battery from wiper 391 and conductor 160per1nits the trunk relay group to resume its talking condition, and the reconnection of wiper 389 to battery through resistance 320 permits lsleeve relay 105 ofthe trunk relay group to reoperate. The release of relay 101 ofv the trunk relay group completes the ringing circuit and ringing current is applied .to the called line as in previous connections. When the called sub- Lscriber answers, cut-oil relay 109 operates and connects up battery and ground through impedance 112 and relay 108. The latter relay operates over the called subscribers loop and removes thev shunting ground from thelower winding of Relay 105 remains operated overits upper high resistance winding, and relay 301 also operates. ing contacts 328 and 330 and closing contacts 329 and 331, reverses the connection of the relays 302 Tland303to trunk conductors 335 and 387; in

other words, ,it reverses the direction of current flow over the trunk line. This reversal operates supervisory equipment in the preceding switches to inform the calling operator that the called '1 subscriber has answered.

Iandthe'release of that relay. Relay 302 opens the circuit of relay 305, whichrestores and closes the circuit of release magnet 318 by way of offnormal contacts 326. Relay 305 also removes ground from holding conductor 392, and the various relays which have been held operated by ground on this conductor are released. Release magnet 313 restores the switch wiper to normal position in the usual way and its circuit is opened at contacts 326 when the normal position is Ireached. The release of the trunk relay group is the same as for previous connections.

Trunk calls In connections extended through the tandem oflice to another oilice, the connector repeater CR operates in exactly the same manner as described for a call to the sub-oilice. As there will ordi narily be more than one trunk between oiiices in connections of this type the connector, repeater may hunt over a number of the trunks before Relay 301, by open-.

finding an idle one. Referring to the testing operations described in the previous connection, it will be recalled that, upon the connectorrepeater being operated to the contacts of a busy trunk, relay 312 operated and caused the wipers of the switch to he stepped ahead to the next set of contacts. In case of a trunk call to another office the next set of contacts may also terminate a trunk, and if this is busy, the relay will remain locked up on the test wiper to ground on the test contact of the second trunk. Relay 311 will re operate after the first step and will again close the circuit of the rotary magnet. In this man ner the wipers of the switch will be advanced step by step until an idle trunk is found, or until a set of contacts following the last trunk of the group is reached. The test contact of the addiwith relay 412 of the trunk relay group RG1 over a circuit which may be traced from battery, winding of relay 412, contacts 429 and 440, conductor 403, test contact and wiper 390, upper winding of relay 315 to grounded conductor 392 over the previously-described test circuit. Sleeve relay 408 of the trunk relay group operates from battery over wiper 389,conductor 402, contacts 420, lower winding. of relay 408, to ground. Relay 412 completes a circuit for relays 409 and 410 at contacts 438, and these relays operate. Relay 409 disconnects highnesistancc relay 413 from across the outgoing trunk by opening contacts 425. Relay 410 shunts the lower high resistance winding of relay 408 by closing contacts 432, thereby preventing the operation of reversing relay 301 of the connector repeater. Relay 410 also connects the upper winding of polarized relay 411 across the outgoing trunk conductors at contacts 430, closes a circuit at contacts 433 for the lower winding of relay 411, disconnects relay 407 from across the trunk conductors at contacts 435, and prepares a circuit for relays "405 and 406 at contacts 436. The 11113 relay of the switch CR1 at the distant office will now operate in series with the upper winding of polarized relay 411, but the latter relay will not operate at this time as its two windings oppose each other. Relay 413 of the trunk relay group in the meantime restores, and completes a circuit for busy lamp L2 at contacts442 to mark the trunk busy at the manual switchboard.

The calling operator now dials the digits necessary to operate switch CR1 and impulse relays 302,304, 306, and 307 of the connector repeater operate in the same manner as described for a call to the sub-ofiice. Relays 309 and 310 operate. in response to the first impulse and remain operated throughout the series of impulses as before.' The circuit of sleeve relay 408 is opened at contacts 353 and that relay restores, and, since battery is connected to wiper 391 of the connector repeater upon the operation of relay 309, a circuit is completed by way of conductor 404, windings of relays 405 and .406, and contacts 423 and 436, to ground. Relay 405 operates, but, due to resistance 323, the current flow in the circuit is insufiicient to operate marginal relay connector 7i and that relay releases.

406. Relay 405 disconnects the trunkconductors 451 and 452 from the bridge including the upper winding of relay 411 and connects these conductors by way of contacts 416 and 418 .to conductors 401 and 402 and thence:over the impulserepeating circuit of the connector repeater. This circuit includes impulse contacts 345 of'relay 306,

at which point the impulses are repeated to the line relay of the switch CR1 atthe distant oiiice. At the end of theseries ofimpulses relays 309 and 310 restore, and in the trunk relay group relay 405 restores and relay 408 operates. .-The

circuit for the line relay of the switch'in the dis tant office is transferred to the bridge including the upper winding of relay 411. Any additional series of impulses required to operate the switches are repeated in the manner just described and the switches are'operated into con-.

nection with the called line.

After establishing the connection with the,

'-relay group to the control circuit of the cord by called line, thecalling operator may. control the auxiliaryoperations of the'switch in the distant. office, such as the starting of ringing or toll offering; by unbalancing the trunk incoming tothe repeater. This is accomplished by operating the ringing key at the calling cord circuit as explained in the Wicks application referred to in the early part of this specificatimn When the trunk is unbalanced by the connection of ground to conductor 385, difierential relay 303 operates and applies battery through resistance 322 to wiper 391 of the connector repeaterl The circuit over which sleeve relay. 403 of the trunk has been held operated is opened at contacts 336 In this case relays405 and 406 both operate as resistance 322 isoi a low value which permits suilicient current flow to operate relay 406. Relay 405 transfers the out going trunk from the bridge in the trunk relay '7 group to the bridge including resistance 319 and contacts 337 of the connect-or repeater. The switches at the distant oiiice are acccrdingly'heid operated over this circuit, and relay 406 applies ground to trunk conductor 451 at contacts 421 to unbalance the trunk to the distant exchange. When theunbalanced condition is removedfrom the incoming trunk the various relays. restore and the apparatus assumes the condition reached at the termination of the iinpulsing.

The called-subscriber is'signalled in the usuai way, and, when the call is answered, the'connector at the distant exchange reverses the direction of current flow over the trunk line. The

two' windings of relay 411 now assist each other polarized relay 411 restores and again connects ground to the upper winding of relay 408. Relay 301 is again shunted and restores, and, by again reversing the direction of current flow over the trunk conductors gives the calling operator. disconnect supervision. The release of the connection is brought about. by the operators withdrawing the plug from the jack, whereupon the circuit for relay 302 of the connector is opened.

Th'is relay restores, followed by -.the return of the-switch to normal in-the usual manner. The

relays of the trunk relay group restore upon the release of the connector repeater. V

In the case of connections completed manu-J ally to the trunk terminating in the relay group RG1, the operations are substantially the same as above described, except in this case relays 409 and 410 are operated from ground by way of jack spring contacts 414 and relay 412 does not operate. Relay 409 connects ground to test conductor 403 by way of contacts 440, 428, and; 441 to mark the trunk busy in the bank of the connector repeaters. Relay 408 operates over a circuit including the sleeve of the plug and jack and opens the circuit of relays 405 and 406. Re-

, lay 410 completes the bridge across the outgoing trunk conductors as before. When the dialling key is operated, the sleeve circuit is opened and relay 408 restores and completes the circuit for relays 405 and 406, which operate. Relay 405 transfers the trunk from the bridge at the trunk way of the tip and sleeve contacts of the jack andplug. The control circuit at the cord includes the impulse contacts of the operators calling device, and upon operating the same the switches-to the distant exchange are directively stepped as required. The operation of the ringing key in the cord circuit produces the same results as the operation of the dialling key, and, further, the resistance of the circuit ,over the ring contact is decreased so that marginal relay 406 is operated and unbalances the outgoing trunk by applying ground to conductor 451 at contacts 421. The connection is releasedin the usual way by the operators withdrawal of the plug of the cord from the jack,

't will be noted that the trunk shown in Fig. 4 is arranged for two-way operation. Calls from the distant exchange to the tandem ofiice will be set up over a connector switch, which, upon seizing the trunk, will operate cut-off relay 450 and switch the trunk conductors from connector CR1 to the conductors extending to the banks of the seizing connector. Ringing current is applied by the connector over conductor 464,,c0n--. tacts 461, trunk conductor 451, contacts 417, condenser 467, contacts 415 and 435, winding of relay 407, condenser 468, contacts 419, trunk conductor 452, contacts 452, conductor 466, back to the connector and ground. Relay 407 operates and completes a circuit for relay 409 at contacts 422. Relay 409 operates, completes a locking circuit for its lower winding by way of contacts 427 and 434, opens the high resistance bridge across the trunk at contacts .425, completes a circuit for line lamp L3 by way of contacts 426, 431, and 437, and at contacts 428 connects ground to release trunk conductor 403 to mark the trunk busy in the banks of the connector repeaters. Relay 413 restores and completes the circuit of busy lamp L2 at contacts 442. Both of the. lamps glow. The line lamp indicates that the call is an incoming one, and the operator accordingly answers by inserting the answering plug of a cord circuit, such as cord C6, into jack J l. Contact-s 414 close when the plug is inserted in the jack, and a circuit is completed for relays 410 and 409 in series. Relay 410 closes the bridge across the trunk conductors as previously described, thereby operating. the ring-cut-ofi relay of the calling connector. In connections of this type thev current flow in the upper winding of relay 411 is in a direction which causes the' t wo windings to assist each other, and the relay opera ates. The circuit completed on the operation of the upper winding of relay 408. V The supervisory signal at the cord circuit is operatedover the sleeve due to the low resistance of the said winding. The operator may then release the trunk bywithdrawing the plug of the cord from the jack, whereupon the relays previously operated all return to normal.

What is claimed is:

1. In an impulse repeating device, a closed in' coming circuit adapted to be momentarily, inter-- rupted to transmit an impulse to the. device, a normally open outgoing circuit, means responsive to the interruption of the incoming circuit for closing the outgoing circuit, and means respon sivev to the reclosureof the incoming circuit for momentarily interrupting the outgoing circuit. 2. In an impulse repeating device, a closed iiicomingcircuit adapted to be momentarily interrupted to transmit an impulse to the device, a normally open outgoing circuit, means responsive to the interruption of the incoming circuit for closing the outgoing circuit, means responsive to the reclosure of the incoming circuit for opening the outgoingcircuit, and means for reclosing the outgoing circuit a predetermined interval after its opening. 7

3. In an impulse repeating device, a closed incoming circuit adapted to be intermittently interrupted to transmit a series of impulses to the device, a normally open outgoing circuit,

means responsive to the interruption of the in-- coming circuit forthe' first impulse of the series, for closing the outgoing circuit, and means responsive to the reclosure of the incoming circuit after each impulse of the series for momentarily interrupting the outgoing circuit.

4. In a telephone system, a trunk, an automatic switch having two talking wipers and an auxiliary wiper, means for operating the switch to connect'with the trunk line via saidwipers, means associated with the trunk and controlled from the switch over one talking wiper and the auxiliarywiper jointly for preparing the trunk for the reception of impulses, and means in the switch for transmitting impulses to the trunk over the other talking wiper and the auxiliary wiper jointly.

5. In a telephone system, an automaticv switch,

a trunk including two conductors, means for operating the switch to connect with the trunk, means responsive to the completion of the corn nection for connecting a bridge across the trunk conductors at a point ahead of the switch, means for transmitting a series of impulses to the switch,

and means responsive to the first impulse of the series for disconnecting said bridge and for connecting the trunk conductors through impulse repeating contacts in the switch. 6. In an automatic switch, two talking wipers and an auxiliary wiper, means for directively opcrating the switch to extend'a connection via said wipers, means for responding to a series of im-.

pulses, and means responsive to said impulses for connecting a source of current to one of the The direction of current a further impulse transmitted over the trunk for connecting a source otcurrent to one talking wiper and for connecting the other talking wiper,

tothe auxiliary wiper through impulse repeathis; contacts in the switch, and means responsive to a specific condition on the trunk forconnecting a difierentsource of current on said one talking wiper and for connecting said other talking wiper to the auxiliary wiper independent of the impulse repeating contacts.

8. In a telephone system, an automatic switch;

a trunk terminating in the switch, a line, a relay for reversing the connectionof the trunk to the switch, means controlled over the trunk for set-.

ting the switch to extend a connection to said line-,means for shunting said relay during and after thesetting of the switch, and means controlled over said line for removing the shunt from said relay to permit the relay to operate.

9. In a telephone system, a group of lines, multiple connections between said lines, means for opening said multiple connections and for extending a call to one of said lines individually, and means controlled over the called line for reclosing said multiple connections.

10. In a telephone system, a group of lines normally connected in multiple, means for extending a call to one of said lines, and means operated prior to the extension of the call for determining whether or not the connections between the lines will be opened when the call is answered.

11.. In a telephone system, a group of lines normally connected in multiple, an automatic switch, means for seizing the switch, means responsive to the seizure of the switch for separating said lines, means for operating the switch to connect with one'of said lines individually, and means controlled over said one line for reconnecting said line while maintaining the connection between the switch and said one line.

12. In a telephone system, a group of lines normally connected in multiple, means for establishing talking connections between different lines in said group and'between lines in the group and said other lines, means for separating the lines of said group during the establishment of any connection, means for maintaining the separation of said line when the connection involves a line of the group and one of said other lines, and means for reconnecting all of the lines of the group when the connection involves two lines of the group.

13. In a telephone system, a switch, a group of lines accessible to the switch, means for operating the switch to connect with one of said lines as a calling line, means for reoperating the switch to connect with a diiierent one of said lines as a called line, and means in the switch controlled over the called line for completing a talking con nection between said calling line and said called line.

14. In a telephone system,a group of lines, a set of contacts for each line, a switch, wipers for the switch, means responsive to the initiation of a call on one of said lines for operating the switch to set the wipers on the contacts of said one line, meansifor reoperating the switch to set the wipers the switch to connect the line to said trunk, means I at the switchboard for answering the call, means at the switchboard for reoperating said switch to connect with a different line as a called line, means for applying ringing current to the trunk to signal the called line, and means responsive to the answering of the call for disabling said last means and for completing a talking connection between the two lines.

16. In a telephone system in which lines are arranged in groups, means for completing con-' nections between lines in the same group and between lines in different groups, means for barring all lines except the wanted line of a group from connections between lines in difierent groups, and means for disabling said last means in connections between lines in the same group.

17. In a telephone system, a group of lines, other lines, a single switch having access to said group of lines, means including said switch for establishing a talking connection between lines in the group or between any line in the group and one of said other lines, means for barring all lines of the group except the wanted line from connections involving one of said other lines, and means operated prior to the establishment of a connection between lines in the group for distrunk for operating the switch to extend a call 19. In a telephone system, a group of lines, a

switch, an operators position, a trunk extending from the position to said switch, means responsive to the initiation of a call on one of said lines for operating said switch to connect with the calling line, means responsive to the completion of the connection for signalling the operator at said position, means at the position for answering the call, means for releasing said switch when the calling subscriber desires a connection with another line in the group, means responsive to the release of the switch for signalling the operator, and means controlled by the operator for reoperating said switch to establish a connection between the calling line and the called line.

20. In an automatic switch, two talking wipers and an auxiliary wiper, impulse receiving means, means controlled by said impulse receiving means for operating the switch to extend a connection over said wipers, and means controlled by said impulse receiving means for repeating impulses to the connection over one talking wiper and said auxiliary wiper in series.

21. In an automatic switch, two talking wipers and a control wiper, impulse receiving means,

means controlled by said impulse receiving means for operating the switch to extend a connection over said wipers, and means controlled by said impulse receiving means for repeating impulses to the connection via said control wiper and one of said talking wipers and for simultaneously exercising an auxiliary controlling function over the other of said talking wipers.

JOHN WICKS. HARRY G. EVERS. 

